1. Field of Invention
The invention relates to a calibration device for calibrating a film hose produced via a blow-extrusion device, by which the film hose can be brought to a desired diameter, with the calibration device comprising at least one film guiding element, by which the film hose can be guided.
2. Description of the Prior Art
Such calibration devices have been known for quite some time. In film hoses exiting an annular extrusion nozzle a calibration of the hose to the desired diameter is necessary in order to obtain a product which shows a consistent format.
However, in practice, film hoses are desired whose diameters are different. This can be achieved, in spite of extrusion nozzles the diameter of whose outlets remains unchanged, in that the so-called film bubbles are impinged with different interior pressures, causing the film bubbles to expand differently wide in the radial direction. Of course, the calibration device must be adjustable to various diameters of the film hoses. Here, calibration devices are used, which can be mechanically adjusted.
EP 1 965 965 A1 discloses a calibration device as mentioned at the outset for calibrating a film hose produced via a blow-extrusion film device, with the calibration device being adjustable to different diameters of the film hose.
It has already proven disadvantageous that the film guiding elements comprising such a calibration device are of limited size. Accordingly, particularly in large diameters, there are wide ranges of external surfaces of the film hose which are not guided by a film guiding element. Additionally, a film guiding element can only be curved for a single diameter so that it can contact with its entire surface the external perimeter of the film hose. Additionally, the construction and the design of such a calibration device is complex and therefore expensive.